This invention relates to electrical lighting apparatus. More particularly, it is concerned with apparatus for selectively controlling the lighting level in several zones from a remote location.
A large percentage of all electric power generated is used for commercial lighting. Most of this lighting employs fluorescent lamps. Recently there has been development effort toward conserving some of this energy through more efficient lamps and ballasts and also through the design of control systems which dim or turn off lamps when they are not needed. Dimming ballasts for fluorescent lamps are expensive and their complicated design often leads to poor reliability. Furthermore, dimming ballasts for fluorescent lamps tend to be inefficient at other than certain current levels, and lamp life is often reduced when a lamp is operated at currents other than at its rated value. Control systems are becoming less expensive as improved ones are developed. However, their installation costs particularly in an existing installation are still a major deterrent to their general acceptance.